Clinical analyzers generally utilize dry chemistry systems and/or wet chemistry systems. Each chemistry system is somewhat unique in terms of its operation. For example, known “dry” chemistry systems typically include a sample supply which includes a number of sample containers, a metering/transport mechanism, and an incubator having a plurality of test read stations. A quantity of sample is aspirated into a metering tip using a proboscis or probe carried by a movable metering truck along a transport rail. A quantity of sample from the tip is then metered (dispensed) onto a dry slide element which is loaded into the incubator. The slide element is incubated and optical or other reads are taken for analyte detection.
A “wet” chemistry system on the other hand, utilizes a reaction vessel such as a cuvette, into which quantities of patient sample, at least one reagent fluid, and/or other fluids are combined for conducting an assay. The assay is also incubated and tests are conducted for analyte detection. The “wet” chemistry system also includes a metering mechanism to transport patient sample fluid from the sample supply to the reaction vessel.
A number of known clinical analyzers incorporate both wet and dry chemistry systems in a single apparatus, and are known as “combinational” clinical analyzers.
When operating clinical analyzers, various problems can be encountered. For example, the sample volume that the analyzer delivers to the reaction cell may vary by sample/patient. In addition, some analytes may have reduced recovery and the recovery may vary by sample/patient. Both of these issues result in what an end user would observe as random bias. Customers usually relate to this error as the lack of fit to a regression line compared to a reference method. In addition, certain controls and proficiency fluids may show lower predictions on a particular analyzer compared to other systems.
A need exists for methods which can overcome these problems and improve the accuracy and consistency of clinical analyzers.